Incomplete BBB and Nonspecific Intraventricular Conduction Delays

Figure 7.9 shows a tracing with an RSR' in V2 that is typical of RBBB, but with a narrower QRS duration of 0.10s or greater and <0.12s You will also note that in this tracing the QRSs are less bizarre, and there are fewer

Delayed Wave
Figure 7.9. Incomplete RBBB displaying an RSR' in lead V2, and mild QRS prolongation with a QRS duration of 0.104 s, but less than the 0.12 s required for complete BBB. Note that few secondary ST and T wave changes are present.

Incomplete BBB and Nonspecific Intraventricular Conduction Delays 49

Figure 7.10. Incomplete LBBB showing a QRS duration of 0.116s with either no R wave or tiny R waves in the right precordial leads (poor R wave progression) and a deep S. The QRS is upright on the left, with only mild secondary ST and T wave changes.

Incomplete BBB and Nonspecific Intraventricular Conduction Delays 49

Figure 7.10. Incomplete LBBB showing a QRS duration of 0.116s with either no R wave or tiny R waves in the right precordial leads (poor R wave progression) and a deep S. The QRS is upright on the left, with only mild secondary ST and T wave changes.

Incomplete Bbb

secondary ST and T wave changes. This tracing falls into the category of incomplete RBBB, which was referred to earlier.

The usual pattern of complete LBBB is altered in similar ways in incomplete LBBB (Figure 7.10). These findings reflect delay in conduction of the impulse by the affected bundle branch, rather than total failure.

Not infrequently, one sees a tracing with QRS prolongation of 0.10 s or greater that does not have a pattern typical of either RBBB or LBBB. Elec-trocardiographers frequently refer to such tracings as showing an intraventricular conduction delay, which is nonspecific (Figure 7.11).

Figure 7.11. Nonspecific intraventricular conduction delay with QRS duration of 0.108s. Pattern in the V leads is not typical of either incomplete RBBB or LBBB,

Figure 7.11. Nonspecific intraventricular conduction delay with QRS duration of 0.108s. Pattern in the V leads is not typical of either incomplete RBBB or LBBB,

Incomplete Bbb
Figure 7.12. Rate-dependent BBB. This patient switches conduction to a RBBB pattern when his rate reaches approximately 85. This rhythm strip is recorded in lead Vq.

Was this article helpful?

0 0

Post a comment